1. Field of the Invention
The present invention refers to a method for treatment of metal baths, i.e. molten metals, by means of materials having a high capability of developping gas or vapour when heated by the molten metal. The invention also refers to a device for the realization of such method.
More particularly, the invention is utilized for the spheroidizing treatment of pig iron, i.e. for the production of spheroidal pig iron by means of to a device for the realization of such method.
More particularly, the invention is utilized for the spheroidizing treatment of pig iron, i.e. for the production of spheroidal pig iron by means of materials apt to spheroidize the graphite contained in the molten iron, such materials usually comprising pure magnesium, magnesium alloys and/or other additives such as calcium, cerium or other rare earth element, and being hereinafter referred to as treatment or spheroidizing material.
2. Discussion of Related Art
For such a treatment of metallic baths, and particularly for the production of spheroidized iron, many methods have already been proposed, such as those characterized by the type of ladle or vessel used, by the placing of the treating material in the ladle, by the timing of contact between treating material and metallic bath, and by using a fixed or a rotating ladle.
Correspondingly, spheroidizing methods are known in open or closed ladles, under a pressure or in pressurized chamber, with the spheroidizing material placed on the ladle's bottom, in a little pit or under a diaphragm or a layer of steel pieces, or immersed in the metal bath using a number of methods, and brought into contact with the metallic bath by tilting the ladle.
The main problem to be confronted with in the sphroidizing treatment of graphite in the pig iron has always been mastering of the quick and violent development of gas or vapour by the treatment material when heated in contact with the metallic bath and keeping and distributing, as long and as much as possible, such gas or vapour within the bulk of molten metal in order to obtain a uniform treatment. Many attempts have been made also in this sense, particularly using closed ladles and devices to send or bring the treating material within the metal bulk.
In any case the treating material when in contact with the fused metal bath always vapourized with a violent and uncontrollable emission of gas or vapours and sparkles.